1. Table 25.1 Clinical differences between
diseases of platelets/vessel wall or of
coagulation factors.
Platelets/vessel
wall diseases
Coagulation
diseases
Mucosal
bleeding
Common Rare
Petechiae Common Rare
Deep
haematomas
Rare Characteristic
Bleeding from
skin cuts
Persistent Minimal
Sex of patient Equal >80% male
Table 25.2 Causes of thrombocytopenia.
Failure of platelet production
Selective megakaryocyte depression
rare congenital defects (see text)
drugs, chemicals, viral infections
Part of general bone marrow failure
cytotoxic drugs
radiotherapy
aplastic anaemia
leukaemia
myelodysplastic syndromes
myelofibrosis
marrow infiltration (e.g. carcinoma, lymphoma,
Gaucher’s disease)
multiple myeloma
megaloblastic anaemia
HIV infection
Increased consumption of platelets
Immune
autoimmune
idiopathic
associated with systemic lupus erythematosus,
chronic lymphocytic leukaemia or lymphoma;
infections: Helicobacter pylori, HIV, other
viruses, malaria
drug-induced, e.g. heparin
post-transfusional purpura
feto–maternal alloimmune thrombocytopenia
Disseminated intravascular coagulation
Thrombotic thrombocytopenic purpura
Abnormal distribution of platelets
Splenomegaly (e.g. liver disease)
Dilutional loss
Massive transfusion of stored blood to bleeding
patients
HIV, human immunodeficiency virus.

2. Table 25.3 Thrombocytopenia as a result of
drugs or toxins.
Bone marrow suppression
Predictable (dose-related)
ionizing radiation, cytotoxic drugs, ethanol
Occasional
chloramphenicol, co-trimoxazole, idoxuridine,
penicillamine, organic arsenicals, benzene, etc.
Immune mechanisms (proven or probable)
Analgesics, anti-inflammatory drugs
gold salts
Antimicrobials
penicillins, rifamycin, sulphonamides,
trimethoprim, para-aminosalicylate
Sedatives, anticonvulsants
diazepam, sodium valproate, carbamazepine
Diuretics
acetazolamide, chlorathiazides, frusemide
Antidiabetics
chlorpropamide, tolbutamide
Others
digitoxin, heparin, methyldopa, oxyprenolol,
quinine, quinidine